1. Field of the Invention
The present invention relates to an apparatus for adjusting a length of an antenna of a radio receiver.
2. Description of the Prior Art
In the conventional car radio receiver, a rod antenna has been used and the rod antenna and the body of the car radio receiver is connected by means of a high-frequency cable.
However, when the high-frequency cable having a long distance is installed, the loss associated with the cable is increased and the noise is easily picked up; furthermore, the capacity of the high-frequency cable is added to that of the tuning circuit to increase the fixed capacity. As a consequence, in the variable capacity system in which the tuning frequency is changed by controlling a variable capacitance, a broad tuning range cannot be established. In addition, a satisfactory reception of radio waves is impossible if the length of the antenna is not appropriate; moreover, the antenna length is apt to be increased to receive particularly an AM signal or the like. In such a case, there has been a disadvantage that an accident may occur, for example, the elongated antenna is prevented by some hindrance and is broken when the car is driven into a garage.